Hello, On Thu, Jan 05, 2023 at 05:18:54PM +0100, Michal Koutný wrote: > I guess similar problem would arise for devices that are "naturally" > slow. > Then: > a) it must have been solved elsewhere in the block layer (but it's > broken), > b) it should be solved generically in the block layer (thus this is only > a partial solution). Hard limits tend to make this sort of problems a lot more pronounced because the existing mechanisms tend to break down for the users which are severely throttled down even while the device as a whole is fairly idle. cpu.max often triggers severe priority inversions too, so it isn't too surprising that people hit severe priority inversion issues w/ io.max. Another problem with blk-throttle is that it doesn't prioritize shared IOs identified by bio_issue_as_root_blkg() like iolatency and iocost do, so there can be very severe priority inversions when e.g. journal commit gets trapped in a low priority cgroup further exacerbating issues like this. Thanks. -- tejun
